Make java-event-log-tags.py create its output directory if it does not exist.

Change-Id: I88ca3e6e70d1ff9db8f1328f18c36abc196e1aad
diff --git a/tools/java-event-log-tags.py b/tools/java-event-log-tags.py
index c63fa20..846d9cf 100755
--- a/tools/java-event-log-tags.py
+++ b/tools/java-event-log-tags.py
@@ -26,6 +26,7 @@
 import cStringIO
 import getopt
 import os
+import os.path
 import re
 import sys
 
@@ -144,4 +145,8 @@
 
 buffer.write("}\n");
 
+output_dir = os.path.dirname(output_file)
+if not os.path.exists(output_dir):
+  os.makedirs(output_dir)
+
 event_log_tags.WriteOutput(output_file, buffer)